1. Field of the Invention
The invention relates to a method for the mounting of a bearing block of a coupling plate on a mounting plate, with the bearing block having a bridge-like shape, being provided with bores at its opposite front and rear ends to accommodate fixing screws, and being fixed in place on the mounting plate by means of the fixing screws and the coupling plate engaging in a central sector on the bearing block, with the attachment of the bearing block to the mounting plate comprising at least one additional form fitting element.
The coupling plate, together with a locking mechanism attached thereto and the bearing blocks, form the fifth-wheel coupling of a towing vehicle.
The mounting plate is screwed to a vehicle chassis and supports the two bearing blocks arranged on the side of the coupling plate, with the latter being firmly screwed to the mounting plate by means of the fixing screws. This screw connection must be arranged in such a way that it will permit a sufficient pre-load force in order to create a high normal force between the underside of the bearing block and the bearing surface of the mounting plate and a permanent friction fit resulting therefrom. This friction fit must be maintained in spite of the forces occurring during driving operation, in particular of any transverse forces while negotiating curves and during braking actions
2. Description of Related Art
From DE 199 52 997 A1, for example, a bearing block is known that does not deform during a vertical stress, or only minimally so. These bearing blocks known from the state of the art are self-supporting. In most cases, their underside represents a straight line so that in the case of vertical stress the bearing block can rest uniformly on the mounting plate via its line-like contact surface. Therefore, the fixing screws used to this end must only absorb the vertical forces that result from their pre-stressing, as well as any operating forces that result when traction forces act upward on the fifth-wheel coupling.
However, such a mounting of the bearing block on the mounting plate is hardly suitable for novel bearing blocks that are not disposed of a straight continuous bearing surface on their underside but that merely bear on the area of the screw connection and that are designed to be self-supporting in their central area and at a distance to the mounting plate. Therefore they can not rest on the mounting plate at the location where according to experience the strongest vertical forces occur, namely in the center. If these bearing blocks are subjected to a lot of stress, they deform to a high degree due to a lack of support in the center, i.e. they bend downward. Due to this fact, both ends of the bearing block will try to give way towards the front and the rear, and very strong horizontal forces occur due to the geometric conditions even with minor vertical forces. In order to absorb these horizontal forces, the tightening torque of the screws that ultimately ensure the friction fit would have to be increased considerably. This, however, is not possible without any problems based on the load-bearing ability of the materials and the available installation spaces. With the high transversal forces that occur during driving operation, this design may lead to a dislocation of the bearing block and, over time, to a loosening of the screw connection as a result thereof. The fifth-wheel coupling could separate from the mounting plate, causing the semi-trailer to do the same from the towing vehicle.
From DE 41 35 288 A1 it has become known to design structures complementary to each other at the bearing blocks and at a headroom adapter attached to the mounting plate to absorb the occurring forces. When the bearing blocks are put in place, the structures intended for each other engage with each other as planned. However, the insertion of the structures designed as casting parts into the bearing blocks or, respectively, into the headroom adapter will lead to a considerable technical effort and correspondingly high costs.